red area is drawn

Fragment.glsl

@@ -0,0 +1,6 @@
+#version 330 core
+out vec4 pixColor;
+
+void main(){
+    pixColor = vec4(1., 0., 0., 1);
+}

Vertex.glsl

@@ -0,0 +1,6 @@
+#version 330 core
+layout (location = 0) in vec2 position;
+
+void main(){
+    gl_Position = vec4(position.x, position.y, 0.0, 1.);
+}

headers/Mandelbrot.h

@@ -3,19 +3,17 @@
 
 #include <QVector2D>
 #include <QOpenGLExtraFunctions>
+#include <QOpenGLShaderProgram>
 
 class Mandelbrot : public QObject, protected QOpenGLExtraFunctions {
 Q_OBJECT
 public:
 	void init();
-	void draw();
+	void draw(GLuint, int, QOpenGLShaderProgram&);
 	void zoom(double);
 public slots:
 	void setIterations(int);
 private:
-	static float* genVertices();
-	GLuint createVAO();
-	GLuint vao;
 	int iterations = 0;
 	double scale = 1;
 	QVector2D translation;

headers/OutputWidget.h

@@ -22,6 +22,13 @@ private:
 	void mouseReleaseEvent(QMouseEvent*) override;
 	void keyPressEvent(QKeyEvent*) override;
 
+	void initShader();
+	static std::vector<QVector2D> genVertices();
+	GLuint createVAO();
+	GLuint vao;
+	int vertCount;
+	QOpenGLShaderProgram shader;
+
 	Mandelbrot mandelbrot;
 };
 

src/Mandelbrot.cpp

@@ -3,12 +3,13 @@
 
 void Mandelbrot::init() {
 	initializeOpenGLFunctions();
-
-	vao = createVAO();
 }
 
-void Mandelbrot::draw() {
-
+void Mandelbrot::draw(GLuint vao, int vertCount, QOpenGLShaderProgram& shader) {
+	shader.bind();
+	glBindVertexArray(vao);
+	glDrawArrays(GL_QUADS, 0, vertCount);
+	glBindVertexArray(0);
 }
 
 void Mandelbrot::zoom(double delta) {
@@ -19,34 +20,4 @@ void Mandelbrot::setIterations(int value) {
 	iterations = value;
 }
 
-GLuint Mandelbrot::createVAO() {
-	GLuint vboId;
-	glGenBuffers(1, &vboId);
-	glBindBuffer(GL_ARRAY_BUFFER, vboId);
-
-	float* vertices = genVertices();
-	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
-
-	GLuint vaoId;
-	glGenVertexArrays(1, &vaoId);
-	glBindVertexArray(vaoId);
-	glBindBuffer(GL_ARRAY_BUFFER, vboId);
-
-	glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), (void*) nullptr);
-	glEnableVertexAttribArray(0);
-
-	glBindVertexArray(0);
-
-	return vaoId;
-}
-
-float* Mandelbrot::genVertices() {
-	return new float[8]{
-			-1, -1,
-			1, -1,
-			1, 1,
-			-1, 1
-	};
-}
-
 

src/OutputWidget.cpp

@@ -1,5 +1,6 @@
 
 #include <iostream>
+#include <QResource>
 #include "../headers/OutputWidget.h"
 
 using std::cout, std::endl;
@@ -8,20 +9,64 @@ void OutputWidget::initializeGL() {
 	cout << "Initialize OpenGL" << endl;
 	initializeOpenGLFunctions();
 	getMandelbrot()->init();
+	initShader();
 
 	auto format = this->format();
 	cout << "OpenGL version: " << format.majorVersion() << "." << format.minorVersion() << endl;
 
+	vao = createVAO();
+
+	glEnable(GL_BLEND);
+	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 	glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
 }
 
 void OutputWidget::paintGL() {
 	glClear(GL_COLOR_BUFFER_BIT);
-	getMandelbrot()->draw();
+	getMandelbrot()->draw(vao, vertCount, shader);
 }
 
 void OutputWidget::resizeGL(int w, int h) {
+	//glViewport(0, 0, w, h);
+}
+
+GLuint OutputWidget::createVAO() {
+	GLuint vboId;
+	glGenBuffers(1, &vboId);
+	glBindBuffer(GL_ARRAY_BUFFER, vboId);
+
+	auto vertices = genVertices();
+	size_t size = vertices.size() * sizeof(QVector2D);
+	vertCount = int(vertices.size());
+	glBufferData(GL_ARRAY_BUFFER, (GLsizeiptr)size, &vertices[0], GL_STATIC_DRAW);
+
+	GLuint vaoId;
+	glGenVertexArrays(1, &vaoId);
+	glBindVertexArray(vaoId);
+	glBindBuffer(GL_ARRAY_BUFFER, vboId);
+
+	glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(QVector2D), (GLvoid const*) 0);
+	glEnableVertexAttribArray(0);
+
+	glBindVertexArray(0);
+
+	return vaoId;
+}
+
+std::vector<QVector2D> OutputWidget::genVertices() {
+	return {
+			{-1, -1},
+			{1, -1},
+			{1, 1},
+			{-1, 1}
+	};
+}
 
+void OutputWidget::initShader() {
+	if (!shader.addShaderFromSourceFile(QOpenGLShader::Vertex, "Vertex.glsl")) close();
+	if (!shader.addShaderFromSourceFile(QOpenGLShader::Fragment, "Fragment.glsl")) close();
+	if (!shader.link()) close();
+	if (!shader.bind()) close();
 }
 
 void OutputWidget::wheelEvent(QWheelEvent *e) {